Welcome! He's sooo handsome!! Thank you for adopting and opening your home to a deserving dog. You're in the right place to learn. Your children also look a little older, which is great as they do better with pets than smaller/younger children. I hope you enjoy it here!

What are your hopes for dealing with hIs dog aggression? What are you expecting? Usually if you post your location (not in the intro section-in the general-intro doesn't get a lot of traffic) there are some members here who can recommend a good trainer near you. Most people here advocate positive reinforcement vs positive punishment-so it'll likely be along the lines of what you and your family are looking for.

Good luck on you journey and be sure to share more pictures when you get a chance.